The eight-part series, based on books by author Tana French, followed the investigation into the death of murdered schoolgirl Katy Devlin and its links to the disappearance of two children decades earlier.
Warning! Spoilers for episode eight ahead.
In the final episode, Katy's older sister Rosalind (Leah McNamara) was revealed to be behind her death. She manipulated Damien Donnelly (Jonny Holden), a hapless witness interviewed several times by the detectives, into carrying out the killing for her.
In a conversation with detective Cassie Maddox (Sarah Greene), she offered an insight into her dark motives.
Rosalind said: "I was proud of Katy. She was a sweetheart, and I didn't hate her at all. It was them. Mammy and daddy. I hated them... their miserable joyless marriage... they had to get married because of me. Being with them is like having a bag held over my head.
"Now all they have is the unwanted Rosalind and the defective Jessica... they have nothing. Now they know what it's like to be me."
Elsewhere in the finale, Cassie left the police force and headed to the UK for an abortion. And she vowed never to see her colleague Rob Reilly (Killian Scott) - whom she slept with in a previous episode - again.
Rob was also finally unmasked as Adam, the boy who survived the 1983 incident that saw two of his close pals disappear. The revelation brought his career with the police to an abrupt end.
Episode eight left a number of questions unanswered. What actually happened to Adam's pals Peter and Jamie? And who exactly was Lexie - Cassie's imaginary friend who was later, somehow, found murdered?
These points potentially set Dublin Murders up for a second series, but it appears a number of viewers weren't happy with the conclusion.
On twitter, one said: "What a complete and utter waste of eight episodes. Too many unanswered questions. Will not be rushing out to buy the books #DublinMurders."
What a load of complete and utter codswallop.
Another wrote: "#DublinMurders what a total waste of my time. I mean, what the hell was it all about? If there is a series two it wont be getting watched!"
A third tweeted: "Future BBC dramas should carry a warning up front that they are not going to answer the main key issues so that you don't waste eight hours of your life with a sense of frustration. #DublinMurders."
Someone else put: "#DublinMurders What a load of complete and utter codswallop."
"Well, that was eight episodes of TV viewing that I will never get back," commented a fifth, adding: "What a waste of time. Rubbish ending."
Not everyone found it frustrating though, with some viewers hailing the Dublin Murders finale as "brilliant" and an example of "great storytelling".
One tweeted: "I think #DublinMurders was fantastic. Had me gripped. Great storytelling, characters, setting. Everything. Loved it."
Someone else said: "Brilliant finale to #DublinMurders, which has been a consistently brilliant drama throughout. Sharp script, two fantastic leads and a police interview room twist at the end to rival Line Of Duty. The fact that questions remained unanswered just made me love it more."
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